Medical delivery devices such as syringes typically include a barrel, a plunger rod reciprocally movable in the barrel, and a stopper attached to an end of the plunger rod. The stopper to be used for the syringe is typically air, and liquid impermeable while also possessing low-friction slidability. Air and liquid impermeability is important for eliminating liquid leakage within the barrel and the introduction of air between an outer face of the stopper and an inner wall of the barrel when charging or discharging the liquid inside the syringe. Low-friction slidability is important for facilitating the charging and discharging of the liquid inside the syringe. In addition to these requirements, a medical syringe, in particular, must not, adversely affect any pharmaceutical composition such as biopharmaceuticals that come in contact with the syringe (e.g., a pre-filled syringe comprising a pharmaceutical composition).
Stoppers for conventional syringes are commonly made of a rubber material such as natural rubber, isoprene rubber or styrene-butadiene rubber which may be vulcanized. Although this type of conventional stopper, has satisfactory air and liquid impermeability, it does not have good low-friction slidability. Accordingly, silicone lubricants are typically applied to both the outer face of the stopper and the inner wall of the barrel such that the stopper can slide within the barrel. However, syringes comprising silicone lubricants cannot be used for pharmaceutical composition and the like because the silicone lubricant can cause inactivation or otherwise impact the efficacy of these pharmaceutical compositions. Therefore, in order to maintain the stability of the pharmaceutical composition, stoppers laminated with a fluoropolymer film have been used. Since the air and liquid impermeability of stoppers may also have an impact on the quality and stability of the pharmaceutical compositions, the stoppers laminated with a fluoropolymer film are required to have high levels of air and liquid impermeability. However, when stoppers laminated with a fluoropolymer film are used with a glass or resin syringe having a hydrophilic or lubricant free inner surface, the stoppers undesirably exhibit poorer air and liquid impermeability than conventional, non-laminated rubber stoppers.
Another problem associated with some fluoropolymer laminates is its ability to maintain air and liquid impermeability while also possessing low-friction slidability. For example, some fluoropolymer laminates function inconsistently and can distort during insertion of the plunger rod into the barrel and/or during movement of the plunger rod within the barrel, which can create leak paths for the liquid. Additional difficulties with some fluoropolymer laminates include poor airtightness due to a rough outer surface especially when manufactured as a skived film.
Accordingly, the need exists for stoppers laminated with a fluoropolymer film that are capable of achieving sufficient contact with a hydrophilic or lubricant free inner surface of a barrel of a glass or resin syringe to achieve high levels of air and liquid impermeability while also maintaining acceptably low break loose and slide forces (i.e., low-friction slidability) but not so much contact that the fluoropolymer film is distorted to create leak paths that decrease air and liquid impermeability.